Methods and apparatus for increasing the number of training and data tones in wireless communications systems

ABSTRACT

Accordingly, systems and methods for managing power when the number of training and data tones are increased in a wireless communications system are provided. An L-SIG field is generated that includes a set of data and pilot tones, wherein the pilot tones are inserted between the data tones in the set of data and pilot tones. A plurality of training tones is added to the L-SIG field before and after the set of data and pilot tones. A symbol is generated that includes the L-SIG field, an L-LTF field, and a data field, wherein the training tones of the L-SIG field provide channel estimates for the data field. Power of the L-LTF field is managed relative to power of the L-SIG field in the generated symbol in a time domain.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. patentapplication entitled “METHODS AND APPARATUS FOR INCREASING THE NUMBER OFTRAINING AND DATA TONES IN WIRELESS COMMUNICATIONS SYSTEMS”, having aserial number of Ser. No. 16/521,241, having a filing date of Jul. 24,2019; which is a continuation of U.S. patent application entitled“METHODS AND APPARATUS FOR INCREASING THE NUMBER OF TRAINING AND DATATONES IN WIRELESS COMMUNICATIONS SYSTEMS”, having a serial number ofSer. No. 16/055,869, having a filing date of Aug. 6, 2018; which is acontinuation of U.S. patent application entitled “METHODS AND APPARATUSFOR INCREASING THE NUMBER OF TRAINING AND DATA TONES IN WIRELESSCOMMUNICATIONS SYSTEMS”, having a serial number of Ser. No. 15/337,093,having a filing date of Oct. 28, 2016; which is a continuation of U.S.patent application entitled “METHODS AND APPARATUS FOR INCREASING THENUMBER OF TRAINING AND DATA TONES IN WIRELESS COMMUNICATIONS SYSTEMS”,having a serial number of Ser. No. 15/043,102, having a filing date ofFeb. 12, 2016; which claim the benefit of the U.S. provisionalapplication entitled “EQUAL TRANSMIT POWER IN FREQUENCY FOR L-SIG INIEEE 802.11Ax PREAMBLE”, having a serial number of 62/115,794, andhaving a filed date of Feb. 13, 2015, having common inventors, andhaving a common assignee, all of which is incorporated by reference inits entirety.

FIELD OF USE

The present disclosure relates generally to wireless communicationsystems, and more particularly to 802.11ax communications systems.

BACKGROUND

The amount of data tones that needs to be transmitted in wirelessnetworks, such as in 802.11 wireless communications systems, continuesto increase. Next generation 802.11ax wireless communications systemsstill rely on legacy protocols that limit the number of tones that canbe used in transmission, for example, in a legacy-long training field(L-LTF) preamble, to 52 tones. This allows 48 to be used as data tonesand the other four as pilot tones. Such limitations due to legacyprotocol and preamble requirements reduce the amount of data that can betransmitted in the next generation 802.11ax wireless communicationssystems.

SUMMARY

Accordingly, systems and methods for managing power when the number oftraining and data tones are increased in a wireless communicationssystem are provided. In some embodiments, a method for transmitting datain a wireless communications system is provided. An L-SIG field isgenerated that includes a set of data and pilot tones, wherein the pilottones are inserted between the data tones in the set of data and pilottones. A plurality of training tones is added to the L-SIG field beforeand after the set of data and pilot tones. A symbol is generated thatincludes the L-SIG field, an L-LTF field, and a data field, wherein thetraining tones of the L-SIG field provide channel estimates for the datafield. Power of the L-LTF field is managed relative to power of theL-SIG field in the generated symbol in a time domain.

In some implementations, the wireless communications system is an802.11ax wireless communications system. In some implementations, thepower may be managed by reducing power of the L-LTF field to correspondto the power of the L-SIG field. In some implementations, power of eachof the data, pilot, and training tones is reduced by 0.3 decibels. Insome implementations, the power is managed by increasing the power inthe L-SIG field relative to the L-LTF field as a result of adding theplurality of training tones.

In some implementations, the plurality of training tones includes first,second, third and fourth training tones, wherein the first tone and thesecond tone are added before the set of data and pilot tones and thethird tone and the fourth tone are added after the set of data and pilottones. In some implementations, the data and pilot tones each have afirst power value, and wherein the training tones are added by addingthe training tones with the first power value.

In some implementations, the symbol includes an L-STF field before theL-LTF field, a repetition of the L-SIG field, and at least one HE-SIGfield that follows the L-SIG field. In such implementations, the datafield may correspond to the at least one HE-SIG field.

In some implementations, the power is managed by scaling down the powerof each tone in the L-LTF field in accordance with 10 log (n/l), whereinn represents a number of data, pilot, and training tones in the L-SIGfield, and l represents a number of data and pilot tones in the L-SIGfield.

In some embodiments, a system for transmitting data in a wirelesscommunications system is provided. The system includes control circuitryconfigured to generate an L-SIG field that includes a set of data andpilot tones, wherein the pilot tones are inserted between the data tonesin the set of data and pilot tones. The control circuitry is configuredto add a plurality of training tones to the L-SIG field before and afterthe set of data and pilot tones. The control circuitry is configured togenerate a symbol that includes the L-SIG field, an L-LTF field, and adata field, wherein the training tones of the L-SIG field providechannel estimates for the data field. The control circuitry isconfigured to manage the power of the L-LTF field relative to power ofthe L-SIG field in the generated symbol in a time domain.

In some implementations, the wireless communications system is an802.11ax wireless communications system. In some implementations, thecontrol circuitry configured to manage power is further configured toreduce power of the L-LTF field to correspond to the power of the L-SIGfield. In some implementations, power of each of the data, pilot, andtraining tones is reduced by 0.3 decibels. In some implementations, thecontrol circuitry configured to manage power is further configured toincrease the power in the L-SIG field relative to the L-LTF field as aresult of adding the plurality of training tones.

In some implementations, the plurality of training tones includes first,second, third and fourth training tones, wherein the first tone and thesecond tone are added before the set of data and pilot tones and thethird tone and the fourth tone are added after the set of data and pilottones. In some implementations, the data and pilot tones each have afirst power value, and wherein the control circuitry configured to addthe training tones is further configured to add the training tones withthe first power value.

In some implementations, the symbol includes an L-STF field before theL-LTF field, a repetition of the L-SIG field, and at least one HE-SIGfield that follows the L-SIG field. In such implementations, the datafield may correspond to the at least one HE-SIG field.

In some implementations, the control circuitry configured to managepower is further configured to scale down the power of each tone in theL-LTF field in accordance with 10 log (n/l), wherein n represents anumber of data, pilot, and training tones in the L-SIG field, and lrepresents a number of data and pilot tones in the L-SIG field.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andvarious advantages will be more apparent upon consideration of thefollowing detailed description, taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a diagram of an illustrative wireless communications systemfor transmitting additional training and data tones in accordance withan embodiment of the present disclosure;

FIG. 2 is a diagram of an illustrative preamble with additionaltraining, pilot and data tones in accordance with an embodiment of thepresent disclosure;

FIGS. 3 and 4 are diagrams of an illustrative power distribution offields in a frequency and time domain in a wireless communicationssystem in accordance with embodiments of the present disclosure; and

FIG. 5 illustrates a process for increasing the number of training anddata tones in a wireless communications system in accordance with anembodiment of the present disclosure.

DETAILED DESCRIPTION

This disclosure generally relates to managing power in the transmissionof additional training and data tones in a wireless communicationssystem. For illustrative purposes, this disclosure is described in thecontext a wireless communications system implementing the 802.11axprotocol. It should be understood, however, that this disclosure isapplicable to any other type of wireless communications system (e.g.,any other orthogonal frequency domain (OFDM), a system implementing anyother 802.11 protocol, or other wireless local or wide area networksystem).

FIG. 1 is a diagram of an illustrative wireless communications system100 for transmitting additional training and data tones in accordancewith an embodiment of the present disclosure. System 100 includescontrol circuitry 110, a wireless symbol generator 120 and a transmitter130.

Control circuitry 110 may be based on any suitable processor orprocessing circuitry. Control circuitry 110 may control some or allcomponents of wireless communication system 100. Control circuitry 110may receive and run instructions for implementing a process fortransmitting additional training and data tones. Such instructions maybe stored in a storage device (not shown) in wireless communicationsystem 100. For example, control circuitry 110 may receive instructionsfor implementing process 500 (FIG. 5).

Control circuitry 110 may receive data from another system component andmay instruct wireless symbol generator 120 to generate a symbol fortransmission of the received data in accordance with the 802.11axprotocol. Wireless symbol generator 120 may generate a symbol 300 (FIG.3) or 400 (FIG. 4) that includes the data and other preamble fields.Wireless symbol generator 120 may provide the generated symbol totransmitter 130 for transmission over one or more antennas to anotherdevice (e.g., a receiver). Transmitter 130 may be any transmittercircuitry that transmits signals in accordance with the 802.11 protocol.

In some embodiments, wireless symbol generator 120 may generate symbol300 or 400 (FIGS. 3 and 4). Symbol 300 may include the followingfields/components: legacy short training field (L-STF) 310, L-LTF 320,legacy signal field (L-SIG) 330, repeat L-SIG (R-LSIG) 340, and highefficiency signal fields (HE-SIGA 350 and HE-SIGB 360). L-LTF 320 mayinclude channel estimation information that is used by a receiver todecode information in HE-SIGA 350 and/or HE-SIGB 360. L-LTF 320 may belimited to transmitting only 52 tones (48 data tones and four pilottones), which also limits the amount of data tones available fortransmission in HE-SIGA 350 and/or HE-SIGB 360. This is because thereare insufficient training tones available in L-LTF 320 for providingchannel estimation for decoding additional data tones in HE-SIGA 350and/or HE-SIGB 360. As such, HE-SIGA 350 and HE-SIGB 360 may be limitedto transmitting 48 data tones. Symbol 400 may include similar fields assymbol 300. Specifically, symbol 400 may include the followingfields/components: legacy short training field (L-STF) 410, L-LTF 420,legacy signal field (L-SIG) 430, repeat L-SIG (R-LSIG) 440, and highefficiency signal fields (HE-SIGA 450 and HE-SIGB 460).

In some embodiments, to increase the number of data tones that can betransmitted in, for example, HE-SIGA 350/450 and/or HE-SIGB 360/460,wireless symbol generator 120 may add a plurality of training tones(e.g., four additional training tones) to L-SIG 330/430. The pluralityof training tones added to L-SIG 330/430 may provide channel estimateinformation for decoding information in subsequent fields, such asHE-SIGA 350/450 and/or HE-SIGB 360/460. By adding the plurality oftraining tones (e.g., four additional training tones), HE-SIGA 350/450and HE-SIGB 360/460 may transmit 52 data tones instead of only 48.

FIG. 2 is a diagram of an illustrative preamble 200 with additionaltraining, pilot and data tones in accordance with an embodiment of thepresent disclosure. Preamble 200 may represent L-SIG 330/430 generatedby wireless symbol generator 120. Specifically, preamble 200 mayinitially include a total of 52 tones that includes a set of data tones220 (e.g., 48 data tones) and pilot tones 230, 232, 234 and 236 (e.g.,four pilot tones). Pilot tones 230, 232, 234 and 236 may be placed atrespective positions −21, −7, 7 and 21, and data tones 220 may bepositioned among pilot tones 230, 232, 234 and 236 at a remaining set ofpositions. Wireless symbol generator 120 may insert a plurality oftraining tones 210 and 212 before and after the set of data tones 220and pilot tones 230, 232, 234 and 236. For example, wireless symbolgenerator 120 may insert two training tones 210 before the set of datatones and pilot tones 230, 232, 234 and 236 and may insert two trainingtones 212 after the set of data tones and pilot tones 230, 232, 234 and236. The resulting preamble 200 (e.g., L-SIG 330/430) may include 56total tones. Although only four training tones 210 and 212 are shown anddescribed, any number of additional training tones may be added to L-SIG330/430.

The addition of the plurality of training tones to L-SIG 330/430 mayresult in power increase in frequency and time for symbol 300/400.Specifically, each tone in L-SIG 330/430 may include a certain amount ofpower, and adding the plurality of training tones may increase theoverall power of L-SIG 330/430 by an amount determined in accordancewith 10 log (n/l), where n is the new number of total tones and l is thelegacy number of total tones. Specifically, power increases by an amountcorresponding to 10 log (56/52)=0.3 dB per tone because 56 tones are nowtransmitted instead of 52. In some embodiments, wireless symbolgenerator 120 may include a power management unit for distributing andmanaging power across frequencies or tones and/or time to address thepower resulting from addition of the plurality of training tones toL-SIG 330/430.

Specifically, wireless symbol generator 120 may control the overallpower of symbol 300/400 in the frequency domain on a per tone basisand/or in the time domain across various fields of symbol 300/400. Insome implementations, wireless symbol generator 120 may control ormanage the overall power in frequency and/or time to satisfy apredetermined threshold (e.g., a threshold defined by the 802.11axprotocol). In some implementations, wireless symbol generator 120 maymanage the overall power to be within 0.3 dB above or below thepredetermined threshold. In some embodiments, the predetermined powerthreshold may be represented by P_(B) in FIGS. 3 and 4. Specifically,P_(B) represents the power of a symbol transmitted by wireless symbolgenerator 120 that includes L-STF, L-LTF, L-SIG, R-LSIG, HE-SIGA andHE-SIGB fields without the addition of the plurality of training tones.

In some embodiments, the power management unit of wireless symbolgenerator 120 may keep the power of the plurality of added tones thesame as the set of data tones 220 and pilot tones 230, 232, 234 and 236.Such an embodiment is illustrated in FIG. 3. In addition, the powermanagement unit of wireless symbol generator 120 may keep the power inother fields of symbol 300 at the same level (P_(B)) as before theaddition of the plurality of training tones. Specifically, each tone inthe set of data tones 220 and pilot tones 230, 232, 234 and 236 may havea first power value. The added tones 210 and 212 may be added with apower equivalent or that corresponds to the first power value. Thisresults in an increase in power over time in L-SIG by 0.3 dB relative toP_(B). In such a case, each field of symbol 300 (FIG. 3) may havedifferent heights (e.g., power amount) over time. Accordingly, becausethe same amount of power is kept the same for each tone in frequency,there is no loss in coverage for L-SIG and the performance of L-SIG isnot degraded by the addition of the plurality of training tones.Although there will be a power increase over time for L-SIG 330 (R-LSIG340) relative to P_(B), the overall average power across symbols doesnot change by a significant amount over the standard power requirementsmeaning such standard power requirements can still be met. As such, theoverall performance of L-SIG 330 remains the same as before the additionof the training tones, and additional data tones (e.g., 52 instead of48) can be included in HE-SIGA 350 and HE-SIGB 360.

In some embodiments, the power management unit of wireless symbolgenerator 120 may keep the power of L-SIG 430 (and R-LSIG 440) in timethe same relative to P_(B) by reducing the power per tone in frequencyin L-SIG 430 (and R-LSIG 440) after adding the plurality of trainingtones to L-SIG 430 (and R-LSIG 440). Such an embodiment is illustratedin FIG. 4. For example, power management unit of wireless symbolgenerator 120 may reduce the power per tone in frequency of each tone inL-SIG 430 (and R-LSIG 440) by 0.3 dB such that power across all thetones including the added tones does not exceed P_(B). In suchcircumstances, the power management unit of wireless symbol generator120 may reduce the power in time of L-LTF 420 relative to P_(B) by anamount that corresponds to the decrease in power per tone of L-SIG 430(and R-LSIG 440). For example, the power management unit of wirelesssymbol generator 120 may reduce the power in time of L-LTF field 420 by0.3 dB. The resulting symbol shown in FIG. 4 has L-LTF 420 with lowerheight (lower power) than other fields of symbol 400 relative to P_(B).By reducing the power in time in other fields of symbol 400 and keepingthe power in time the same in L-SIG field 430 as it was before theaddition of the plurality of training tones, there may be loss incoverage for L-SIG. Namely, the performance of L-SIG may be degraded bythe addition of the plurality of training tones. Specifically, while thepower per tone in L-SIG 430 (R-LSIG 440) is reduced, the overall powerin time remains unchanged for L-SIG 430 (R-LSIG 440) relative to P_(B)and the power in time of L-LTF 420 is reduced. As such, the overallperformance of L-SIG 430 may be degraded compared to the performance ofL-SIG 430 before the addition of the training tones, and additional datatones (e.g., 52 instead of 48) can be included in HE-SIGA 350 andHE-SIGB 360.

In some embodiments, the receiver may scale the channel estimates inaccordance with the power increase or decrease provided by the powermanagement unit of wireless symbol generator 120. In someimplementations, the power management unit of wireless symbol generator120 may inform the receiver whether and by how much power is increasedor decreased by the addition of the plurality of training tones. Thereceiver may use this information to scale the channel estimates fromthe L-LTF 320 up or down. For example, the receiver may scale thechannel estimates from L-LTF down and/or the channel estimates fromL-SIG 330, RL-SIG 340, HE-SIGA 350, HE-SIGB 360 up.

FIG. 5 illustrates a process 500 for increasing number of training anddata tones in a wireless communications system in accordance with anembodiment of the present disclosure. At 510, an L-SIG field thatincludes a set of data and pilot tones is generated. The pilot tones areinserted between the data tones in the set of data and pilot tones. Forexample, preamble 200 includes a set of data tones 220 and pilot tones230, 232, 234 and 236 (FIG. 2).

At 520, a plurality of training tones is added to the L-SIG field beforeand after the set of data and pilot tones. For example, training tones210 are added before the set of data tones 220 and pilot tones 230, 232,234 and 236, and training tones 212 are added after the set of datatones 220 and pilot tones 230, 232, 234 and 236 (FIG. 2).

At 530, a symbol that includes the L-SIG field, an L-LTF field, and adata field is generated. The training tones of the L-SIG field providechannel estimates for the data field. For example, wireless symbolgenerator 120 generates symbol 300, which includes L-LTF 320, L-SIG 330and data fields (e.g., HE-SIGA 350 and HE-SIGB 360) (FIG. 3) or symbol400, which includes L-LTF 420, L-SIG 430 and data fields (e.g., HE-SIGA450 and HE-SIGB 460) (FIG. 4).

At 540, power of the L-LTF field is managed relative to power of theL-SIG field in the generated symbol in a time domain. For example, thepower management unit in wireless symbol generator 120 may increase thepower of L-SIG 330 and keep the same power in other fields, such asL-LTF field 320 (FIG. 3). Alternatively or in addition, the powermanagement unit in wireless symbol generator 120 may reduce power pertone in L-SIG 430 and may reduce the power in time of another field. Forexample, the power management unit in wireless symbol generator 120 mayreduce the power in time of L-LTF 420 by an amount that corresponds tothe amount of power per tone decrease in L-SIG 430 (FIG. 4).

The foregoing describes methods and an apparatus for increasing thenumber of training and data tones in a wireless communications system.The above-described embodiments of the present disclosure are presentedfor the purposes of illustration and not of limitation. Furthermore, thepresent disclosure is not limited to a particular implementation. Forexample, one or more steps of the methods described above may beperformed in a different order (or concurrently) and still achievedesirable results. In addition, the disclosure may be implemented inhardware, such as on an application-specific integrated circuit (ASIC)or on a field-programmable gate array (FPGA). The disclosure may also beimplemented in software by, for example, encoding transitory ornon-transitory instructions for performing the process discussed abovein one or more transitory or non-transitory computer-readable media.

What is claimed is:
 1. A method for transmitting data in a wirelesscommunications system, the method comprising: providing an L-SIG fieldthat includes a set of data and pilot tones and includes a plurality oftraining tones, wherein the pilot tones are positioned between the datatones in the set of data and pilot tones, wherein the plurality oftraining tones are positioned before and after the set of data and pilottones; generating an L-LTF field and a data field; managing power of theL-LTF field relative to a number of tones of the L-SIG field; whereinthe number of tones of the L-SIG field correspond to the total number ofdata, pilot, and training tones of the L-SIG field.
 2. The method ofclaim 1 wherein the managing the power includes managing power of theL-LTF field relative to a number of tones of the L-SIG field in a timedomain.
 3. The method of claim 1 wherein the training tones of the L-SIGfield provide channel estimates for the data field.
 4. The method ofclaim 1, wherein the wireless communications system is an 802.11axwireless communications system.
 5. The method of claim 1 transmitting,via a wireless transmitter, the data field based on transmissionparameters specified in at least the L-SIG field.
 6. The method of claim1, wherein the plurality of training tones includes first, second, thirdand fourth training tones, wherein the first tone and the second toneare positioned before the set of data and pilot tones in the L-SIG fieldand the third tone and the fourth tone are positioned after the set ofdata and pilot tones in the L-SIG field.
 7. The method of claim 1,wherein the data and pilot tones in the L-SIG field each have a firstpower value, and wherein the training tones have the first power value.8. The method of claim 1, wherein managing the power comprises scalingdown the power of each tone in the L-LTF field in accordance with 10 log(n/l), wherein n represents a number of data, pilot, and training tonesin the L-SIG field, and l represents a number of data and pilot tones inthe L-SIG field.
 9. The method of claim 1 further comprising: wirelesslytransmitting the L-SIG field, the L-LTF field, and data field. 10.Circuitry for a system for transmitting data in a wirelesscommunications system, the circuitry comprising: control circuitryconfigured to: provide an L-SIG field that includes a set of data andpilot tones and a plurality of training tones, wherein the pilot tonesare positioned between the data tones in the set of data and pilottones, wherein the plurality of training tones are positioned before andafter the set of data and pilot tones; provide an L-LTF field and a datafield, and manage power of the L-LTF field relative to a number of tonesof the L-SIG field, wherein the number of tones of the L-SIG fieldcorrespond to the total number of data, pilot, and training tones of theL-SIG field.
 11. The circuitry of claim 10 wherein: wherein the trainingtones of the L-SIG field provide channel estimates for the data field.12. A system for transmitting data in a wireless communications systemcomprising the circuitry of claim
 10. 13. The system of claim 12,wherein the wireless communications system is an 802.11 ax wirelesscornmunications system.
 14. The circuitry of claim 10, wherein thecontrol circuitry configured to manage the power is further configuredto reduce power of the L-LTF field to correspond to the power of theL-SIG field.
 15. The circuitry of claim 14, wherein the controlcircuitry configured to reduce power is further configured to reducepower of each of the data, pilot, and training tones by 0.3 decibels.16. The circuitry of claim 10, wherein the control circuitry configuredto manage the power is further configured to increase the power in theL-SIG field relative to the L-LTF field as a result of the plurality oftraining tones in the L-SIG field.
 17. The circuitry of claim 10,wherein the plurality of training tones includes first, second, thirdand fourth training tones, wherein the first tone and the second toneare positioned before the set of data and pilot tones in the L-SIG fieldand the third tone and the fourth tone are positioned after the set ofdata and pilot tones in the L-SIG field.
 18. The circuitry of claim 10,wherein the data and pilot tones and the plurality of training toneseach have a first power value.
 19. A method for transmitting data in awireless communications system, the method comprising: providing usingcircuitry, an L-SIG field that includes a set of data and pilot tonesand includes a plurality of training tones, wherein the pilot tones arepositioned between the data tones in the set of data and pilot tones,wherein the plurality of training tones includes first, second, thirdand fourth training tones, wherein the first tone and the second toneare positioned before the set of data and pilot tones in the L-SIG fieldand the third tone and the fourth tone are positioned after the set ofdata and pilot tones in the L-SIG field; generating an L-LTF field and adata field.
 20. The method of claim 19 further comprising: wirelesslytransmitting the L-SIG field, the L-LTF field, and data field.
 21. Themethod of claim 20 wherein the wirelessly transmitting includestransmitting the data field based on transmission parameters specifiedin at least the L-SIG field.
 22. The method of claim 19 wherein thetraining tones of the L-SIG field provide channel estimates for the datafield.